It is conventional practice in restaurants, and the like to employ ventilating hoods above cook tops, deep fat fryers, and other cooking units and by use of fans to draw heated cooking vapors, often including volatilized grease, out of the cooking area through the hood and a communicating exhaust stack. In the absence of grease filters in the hood, a portion of the grease particles and the like entrained in the air captured by the hood pass through the exhaust stack to form undesirable environmental contamination. A remaining portion of the volatilized grease entrained in the airstream contacts and tends to condense on the cooler surfaces inside the hood and exhaust stack, eventually forming an inflammable material which, being close to the heat of the cooking unit, may create a potential fire hazard. To reduce the quantity of volatilized grease available passing to the outside atmosphere and condensing on the inner stack and hood surfaces, cooktop hoods are frequently provided with grease filters. Effective grease filters eliminate much of the environmental contamination and greatly slow grease buildup, by entrapment of substantial portions of the entrained volatilized greases and the like in the grease filter.
Condensed grease and the like will relatively quickly build up on the surfaces of the grease filter, and to a lesser extent may gradually build up on the interior surfaces of the hood and stack beyond the filter. If this buildup is allowed to continue, the filter will gradually clog and loose filtering efficiency and the grease buildup in stack and filter may eventually be a fire hazard. Unfortunately, it is messy and time consuming to attempt to clean the interoir surfaces of the hood and exhaust stack, where access thereto is obtainable, and for that matter even to clean the grease filter.
Prior attempts of which I am aware, to deal with this problem, have been fragmentary at best.
For example, U.S. Pat. No. 3,805,685 (Carnes) provides fixed wash liquid pipes within the hood, disposed on opposite sides of a filter shielded from the cooking unit by a series of intervening baffles, wherein nozzles on the fixed pipes spray a wash liquid onto opposite sides of the filter simultaneously for cleansing purposes. However, it is not permissible to use this approach where one side of the filter unit is directly (i.e. visibly) exposed to the cooking unit since wash liquid from the spray nozzles, or bouncing off the exposed side of the filter unit, would fall on and contaminate the exposed cooking surfaces of the cooking unit. Further, with such fixed spray nozzles, it is difficult to obtain uniform application of the washing liquid to the filter unit faces. Also in such prior apparatus, no provision is made for cleaning the interior surfaces of the hood and exhaust stack beyond the filter.
Accordingly, the objects of this invention include provision of:
(1) A filtered ventilating system for a cooking unit, providing for rotating application of wash liquid sprays to interior contaminant and grease collecting surfaces of the hood and exhaust stack, and simultaneously to the back (stack facing) surfaces of a filter unit supported by the hood.
(2) A system, as aforesaid capable of cleaning with such wash liquid, both the inlet and outlet sides of the filter unit despite mounting of the filter unit to expose one of its sides directly to the cooking area and despite absence of wash down pipe spray nozzles between the filter unit and cooking unit.
(3) A system, as aforesaid, in which the filter unit shields the cooking area from wash down spray liquid and which is particularly adapted to use filter units generally of labyrinth type, e.g. employing opposed troughlike baffles which impart a sinuous flow pattern to cooking fumes traveling therethrough.
(4) A system, as aforesaid, in which the filter unit is readily reversed, side-for-side, in the hood, while yet remaining connected positively to the hood for ease in controlling and supporting the filter units during such reversal.
(5) A system, as aforesaid, which permits rotative driving, from a common motor, of wash down pipes extending transverse to one another in said hood and exhaust stack as well as providing for independent supply of wash liquid thereto from a common wash liquid source.
Other objects and purposes of this invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.